Flow assurance considerations in Field development

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Flow assurance considerations in hydrocarbon field development and planning

Prof. Milan Stanko (NTNU)

Issues

• microorganism growth

Naphtenates

Foam

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TPG4230 - Field development and operations Prof. Milan Stanko (NTNU)

Notes for Youtube video nr. 18

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Hydrates

https://www.youtube.com/watch?v=Oz4NLXfdqpA

Hydrates ‐ conditions

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Hydrates ‐ conditions

Wax

Paraffins (C18 ‐ C36) TAKEN FROM EQUINOR

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Wax

Wax

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Wax

y = ‐0.1230x + 5.0818

R² = 0.9974

0.000

2.000

4.000

6.000

8.000

10.000

12.000

‐60.0 ‐40.0 ‐20.0 0.0 20.0 40.0 60.0

wax wt%

Temperature, [C]

Wax

y = ‐0.1230x + 5.0818

R² = 0.9974

0.000

2.000

4.000

6.000

8.000

10.000

12.000

‐60.0 ‐40.0 ‐20.0 0.0 20.0 40.0 60.0

wax wt%

Temperature, [C]

dr

dT

dT

dCBn

owax

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Wax

Asphaltenes

TAKEN FROM EQUINOR(KALLEVIK)

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Scale

+

p↓T↑

TAKEN FROM EQUINOR (SANDENGEN)

Erosion

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Slugging

https://www.youtube.com/watch?v=j59QLHsTs_c

Slugging – impact on separator operation

LAL: Level alarm lowLAH: Level alarm highLALL: Level alarm low lowLAHH: Level alarm high high

https://pubs.spe.org/en/ogf/ogf‐article‐detail/?art=1028

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Slugging – impact on separator operation

Slugging – slugcatcher handling slugs

https://www.youtube.com/watch?v=LKLW5284adI

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Corrosion

Oil‐water emulsions

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Foam

https://www.arab‐oil‐naturalgas.com/foam‐in‐oil‐gas‐separators/

https://www.crodaoilandgas.com/en‐gb/discovery‐zone/functions/foamers

Flow assurance

issue

Causes Potential Consequences Prevention/solution Tools available for analysis

Hydrates • Small gas HC molecules• Free water• Begin to form at a given p and

T (low T, high P) given by thermodynamic equilibrium of the hydrate phase.

• Blockage of flowlines and pipelines

Reduce the hydrate formation region:•Continuous or on‐demand injection of chemical inhibitor (MEG or MEOH)Stay out of hydrate formation region:•Improve thermal insulation•Electric heatingOthers:•Cold flow*•Water removal and gas dehydration*

To determine Hydrate formation conditions:•Laboratory tests•Empirical correlations•Thermodynamic simulators (e.g. Hysys, PVTsim, Unisim)To determine p and T along the pipe:•Multiphase simulator (Olga, LedaFlow).•Computational fluid dynamics (CFD)

Wax • Composition of the crude oil• Begins to form at given p and

T due to changes in solubility• Cold wall

In wells, flowlines and pipelines:•Increase pressure drop (pipe roughness)•Reduction of cross section area•Pipe blockage•Changes fluid rheology•Gelling (problem for startup)

• Pigging• Thermal insulation • Electric heating• Chemical inhibitors• Chemical dissolvers• Pipe coating• Cold flow*

• Laboratory tests• Transient multiphase simulators (e.g. Olga,

LedaFlow)• Computational fluid dynamics (CFD)

Slugging • Dynamics of multiphase flow of liquid and gas

• Reduction of rate• Liquid accumulation on low

points

• Fluctuating liquid and gas input to processing facilities

In flowlines and pipelines:• Vibration• Added pressure drop• Fatigue

• Change separator size• Pipeline dimensioning• Maintain flow above minimum flow rate• Gas lift in riser base• Choking topside• Pipeline re‐routing• Subsea separation*

• Transient multiphase simulator (OLGA, LEDA)• Structural analysis (usually with FEA, e.g. Ansys)• Laboratory experiments

Scaling • Changes in solubility (e.g. changes in P and T conditions, changes in pH, mixture of incompatible water, CO2 injection)..

• Irregularities on surface

In wells, pipelines and flowlines:•Reduction of cross section area•Pipe blockage•Malfunctioning of valves and equipment

• Continuous injection of chemical inhibitors• Dilution by adding more water • Chemical dissolvers• Mechanical removal• Coating

• Laboratory tests• Simulation tools

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Flow assurance

issue

Causes Potential Consequences Prevention/solution Tools available for analysis

Erosion • Sand production• High flow velocities• Liquid droplets in the gas• Gas droplets in the liquid

In wells, pipelines and flowlines:•Structural damage•Vibration•Leaks•Corrosion

• Change geometry• Replacement and maintenance of

components• Reduce flow rate (reduce formation

drawdown)• Sand separation*• Coatings

• Standards (DNV‐RP‐0501)• Computational fluid dynamics• Laboratory testing

Corrosion • Water• O2

• CO2

• H2S

• Leaks• Integrity

• Coatings• Material selection• Surface passivation

• Laboratory testing

Emulsions • Emulsification agents in the crude

• Mixing, shear when flowing through valves, chokes, etc

• Added pressure drop• Increased separation time

• Injection of demulsifiers• Heating

• Laboratory tests• Multiphase models

Asphaltenes • Crude with asphaltenes• Pressure reduction• Addup of light hydrocarbon

components

• Blockage of formation, well, flowline and pipeline

• Loss of equipment functionality• Emulsification and

foamification

• Mechanical removal• Chemical injection

• Laboratory tests• Some simulation tools

Measures and consequences

• Chemical injection• System design, e.g.

o pipe and component insulation o heat tracing o dead legs o pipeline routing

• Well intervention needs• Water injection strategy• Define procedures when shutting down

and starting up• Ensure proper distribution of chemicals

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Example of chemical injection program

Release and disposal of chemicals

From Ivar Aasen PDO, Del 2

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From Johan Castberg PDO, Del 2

More about production chemicals

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Flow assurance evaluation during field planning

Business case identification

Project planning

Project execution

Operations Decommissioning

Discovery DG0 DG2 DG4DG1 DG3

• Detect potential showstoppers and communicate technical constraints and repercussions to field planner

• Laboratory tests

Business case identification

Project planning

Project execution

Operations Decommissioning

Discovery DG0 DG2 DG4DG1 DG3

Refine the flow assurance strategy‐More laboratory tests‐Management plan‐prediction of p and T‐Study of startup and shutdown‐System design and verification‐FIV

Flow assurance evaluation during field planning

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Injection of production chemicals subsea

Injection of production chemicals

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Umbilicals, injection of production chemicals

Umbilicals, injection of production chemicals

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Injection of production chemicals – template wells

Injection of production chemicals – template wellsCONNECTION TOUMBILICAL

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Injection of production chemicals in well

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DEAD LEG

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Tools for analysis

• Laboratory tests of fluids (oil, gas, water)• Steady state flow simulators (Hysys, Gap, Pipesim, Olga,

Leda, FlowManager)• Transient flow simulators (Olga, LedaFlow,

FlowManager, Hysys)• Thermodynamic or PVT simulators (PVTsim, Hysys)• Standards (DNV, API)• CFD simulation for 3D flow analysis of pressure and

temperature (Comsol, Ansys)• Finite element analysis for structural analysis and heat

transfer in solids (Abacus, Ansys)

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Flow assurance considerations in Field development

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